At present there is a need for an inexpensive tandem bicycle, which is not being met by the very expensive rigid-frame tandems available in bicycle shops. The rigid-frame tandems are not only expensive, but are also inefficient when only one person wishes to ride the tandem because of the extra length and weight and the decreased maneuverability.
Several prior-art devices have joined a leading bicycle to a trailing bicycle whose front wheel has been removed in order to form a tandem with three wheels. Thus, U.S. Pat. No. 1,300,343, issued to J. A. Carswell, shows a trailing bicycle connected to a leading bicycle by coupling links 10, made in mirror image, which bolt onto the frame of a leading bicycle and include offset hubs 16 with bearings, to which the front forks of a trailing bicycle are fastened. The Carswell device requires two expensive, complex-shaped pieces and bearings.
German patent DE 37 29 879, to Konig, depicts two bicycles connected by attaching the front forks of a trailing bicycle to either the frame or the axle of the leading bicycle. The Konig patent is believed to be the basis of the "Cyclemate" device advertised in the August 1994 issue of Popular Science magazine.
John Strong, in U.S. Pat. No. 4,458,908, shows a tandem bicycle much like that of Carswell or Konig except that a complicated mechanism is deployed between the frame and the forks of the trailing bicycle. Strong explains at col. 4, line 17 that his device allows the trailing "section" (bicycle) "to tilt, to bend, and to articulate independently from a leading section" which in Strong's parlance means that the trailing bicycle may roll, pitch, and yaw relative to the leading bicycle. At col. 8, line 5, he adds, "The invention resides in . . . allowing independent tilting [rolling], articulating [yawing], and, in the preferred embodiment, bending [pitching] . . . In its most general terms, the invention resides in . . . provision of means to accommodate the tilting [rolling]."
Strong's forks are rigidly attached to one another. All hinging is within the headset. In FIG. 3, it is seen that Strong's front forks 70 are not separated sufficiently to allow fastening directly to the axle 62.
None of the above-listed patents discloses mounting a trailing bicycle to a leading bicycle without the provision of special hardware, such as the brackets of Carswell.
The prior art does not show a single bicycle that is adapted to be interchangeably used as a trailing or a leading bicycle when combined with another identical bicycle nor any bicycle that, when combined with other identical bicycles, is able to form a chain of more than two bicycles.
The prior art does not disclose any front fork having springs to resist yawing of a front fork wheel axis, nor such springs combined with fork compression springs.
The prior art does not disclose or suggest a bicycle that is only slightly more expensive than a regular bicycle, but is also easily adapted to tandem as well as to solo use.